Internet speed drops when streaming only at certain times?

I stream on Twitch and I haven't had any internet issues until a month ago. It started that the speed went down and up again at a certain time. So I start streaming from 6 p.m. And the problem starts around 8 p.m. To 11 p.m. At 8 p.m. It starts with a few discarded frames and it gets worse and worse and the red light appears more and more frequently.

On some days it is so bad that hundreds of thousands of frames are discarded at the end. I do not understand why.

-I contacted the internet provider several times

-Tried new cables

-tried other servers in OBS

-Always restarted the modem

-Speed test done

It's always the same, but I don't know why it happens at the exact time I'm streaming! Can someone help me?

I often have the same problem but lately it works. I suspect that it is because at these certain times of the day more people use the Internet than when otherwise (video conversations etc.)

Probably the best internet usage is to call the provider, say you insist that the problem is solved, for example, a period of 4 weeks and change the provider, the period should expire since then I have constantly 80mbits down and 30mbits upstream

If it's an apartment building, can it be related to activities from other residents? That this is the time most people switch to Netflix?

Very many now have home offices or homeschooling. You can guess 3 times why your internet speed is getting worse

No, when I stream I only use the internet. We're only two people in the apartment.

But in the speed test I get a full 10 mbit which I also get with other programs.

LTE internet connection? Then that would be simply normal at that time